Last night's Supernatural episode, "Blood Brothers," was great for two reasons. One, it was artfully written (by Ben Edlund) and brought us back to the season's arc while also telling a completely self-contained story. And two, it offered us a way to understand the emotional connections in Sam and Dean's lives as battlefield romances - the bonds of soldiers whose intense feelings for each other are cleaner and more binding than anything they might get out of a heterosexual romance.

Spoilers ahead!

This episode brought back Bennie, the vampire who helped Dean escape from Purgatory. His hold on Dean is similar to Sam's - the two of them have fought together and had each other's backs. In fact, there's a way that Dean is actually closer to Bennie these days than he is to Sam. After all, Bennie had Dean's back in Purgatory while Sam was off making puppies with emotionally wounded veterinarian chick.

When Bennie slaughters a whole bunch of vampires and gets his legs nearly chewed off, he calls Dean for help. And Dean runs off to help his vamp pal, telling Sam that he's got to do something "personal." Immediately, there's a tension here that feels romantic more than anything. Dean has been cheating on Sam with another "brother," and Sam is jealous and worried.

As we learn more about Bennie's backstory, we also get a rare glimpse of a fully humanized monster. Usually, monsters on Supernatural are there to be hunted and/or ganked. But Bennie fell in love with a human before he died, and this turned him away from his vampiric ways. Once, Bennie ran with a nest of vampires who owned a fleet of yachts, chasing down their quarries at sea. ("So you were vampirates!" Dean says. Bennie is not amused.) After meeting his human lady love, however, Bennie ran from a life at sea and settled down with her - until his maker showed up, killing Bennie and turning Bennie's girlfriend into his new vampire lieutenant.

Needless to say, Bennie's goal on Earth is to hunt his maker down and "leave a crater behind." Dean agrees to help, while Sam frantically tries to reach Dean on his cell. Again, it feels like Dean is cheating on Sam here - he's hunting with another man, and keeping it from Sam. Plus the more we know about Bennie, the more he seems like a vampire version of Sam. Like Sam, he struggles with his dark side, but has managed to pull himself together.

And in the end, after Bennie and Dean find the vamp nest, Dean does for Bennie what he's done for Sam many times. He saves Bennie's ass by killing the woman Bennie loves. Oh, and one interesting detail we glean from the vamp killing: These vamps appear to have no idea that they'll go to Purgatory when they die.

As this drama is unfolding, we get more flashbacks to Purgatory. We see how Bennie became a true friend to Sam and even to Cas, despite his misgivings. He helped them fight off monsters in many situations where he didn't have to do it. And now that we realize that his goal in returning to Earth was to stamp out the evil of his maker, he's starting to seem more and more like he's on the Winchesters' team. Or at least Dean's team, since Sam doesn't even know that he exists. We also learn that Cas was a real liability for Dean and Bennie in Purgatory - he was a "beacon" to the monsters, especially the Leviathans, who are constantly trying to kill them. Plus, they brought him along without ever knowing whether they'd be able to pull him through the human exit to Earth.

All the killing and sacrificing leads Cas to wonder crazily, at one point, what happens to monsters who die in Purgatory. Maybe we'll never know.

We have the obligatory Sam flashbacks too, where we find out that he worked as a handyman for a while before hooking up with damaged vet lady. These flashbacks weren't as bad as the glowy flower field ones from two weeks ago, but they were still kind of stiff and awful. She thought Sam was a creep! He thought she was a person who thought he was a creep! And so on.

And now it's time to process our feelings because this all led up to a pretty powerful final scene in the episode. Dean has tipped Sam off to where he's hunting vamps, so Sam races out to meet Dean and Mr. Mysterious. Meanwhile, Dean and Bennie have just killed Bennie's entire vamp family, including Bennie's one true love (whom he no longer loves because she likes to eat people now). As Dean and Bennie climb aboard their boat to return to shore, Dean asks Bennie, "Are you good?" Bennie gives him a zillion-yard stare, and says something manly and sailor-like about how he isn't entirely sure. A difficult but companionable silence settles between the two men.

When they come ashore, Sam finally meets the brother that Dean has been cheating on him with. And he's a monster! Sam almost kills Bennie without a second thought, but Dean stays his hand with a shake of the head. "You have a lot to talk about," Bennie says in his usual taciturn way, and leaves. Fade to freakin black. Ouch!

So Bennie knew about Sam, but Sam didn't know about Bennie. I really hope we get to see more of Bennie this season, because he's one of the most interesting new characters to show up in this series for quite some time.